1. Field of the Invention
The present invention relates to a wideband planar dipole antenna and, more particularly, to a single-surface/double-surface wideband planar dipole antenna that is manufactured by using a symmetric or asymmetric mechanism.
2. Description of Related Art
Digital TV broadcasting systems have developed very quickly in recent years. In order to receive all programs in the UHF band, a digital TV UHF antenna with the operational frequency from 470 MHz to 860 MHz is usually required. Existent antennas used in the UHF band are commonly yagi antennas or rod antennas, both of which are illustrated below.
A yagi antenna is composed of many antennas at different lengths, and achieves the wideband effect by combining different resonance frequencies. This kind of antenna has a better receiving performance when installed outdoors. The yagi antenna, however, is bulky and heavy, and is therefore not suitable to the applications of indoor digital TV systems. A rod antenna is based on the principle of monopole antenna. The length of this kind of antenna is designed to be a quarter of the wavelength (λ/4). Commercially, a rod antenna is spirally wound to shorten its effective length, and a ground plane is finally added at the base of the antenna to finish a rod antenna with a minimized size. This kind of antenna has a slightly inferior receiving performance, and is less convenient in use. The above two kinds of antennas have a high manufacturing cost, and is too large in size.
In consideration of the above drawbacks of existent digital TV antennas, i.e., bulky size, inconvenient portability and high cost, the present invention aims to provide a wideband planar dipole antenna to solve the above problems in the prior art.